Pauline Chanut, Elsa Hernandez, Catherine Kern, Christine Garcia
2021, 26 TH IFSCC CONFERENCE
Human skin pigmentation is a complex biological process responsible for the color and tanning of the skin. Key players include melanocytes that synthesize melanin into specific intracellular structures called melanosomes and neighboring keratinocytes that receive and distribute it in upper layers of the skin. They constitute the functional epidermal melanin unit. Melanogenesis can be regulated by both intrinsic individual features and external factors such as UV exposure with more than 150 described genes acting for example on melanin synthesis or melanosome transport. Mechanisms behind tanning are a stimulation by the sun, in particular UV-A and UV-B rays, of melanogenesis with migration of melanins into keratinocytes to protect them from DNA damages. Many products for artificial tanning exist such as the most known self-tanner dihydroxyacetone (DHA) involving the biochemical Maillard reaction with amino acids present in the skin. However, DHA acts chemically on the upper layers of the skin (stratum corneum) which induces reactive oxygen species. Moreover, its use is not optimal due to uneven skin coloration, high degradation rate and it has no protective effect on our cells DNA as melanin does. To combine tanning with less sun exposure, a new esterified lipoaminoacid, ELA (INCI: Isosorbide (and) Capryloyl/Capryloyl Leucine Isosorbide Esters), was developed by bio-inspiration with a bio-sourced aminovector of leucine, an amino acid that builds several proteins and which is also particularly involved in cutaneous pigmentation, together with an isosorbide derived from starch that could improve delivery and efficacy of the ingredient . ELA was biologically evaluated on the melanogenesis and skin tanning processes. The production of melanin was first measured on murine and human melanocytes. Its capacity to regulate melanosome transfer was also investigated on a melanocytes/keratinocytes co-cultivation model. Regulations of ELA were then analyzed at the melanogenesis-related gene level in human pigmented reconstructed epidermis to go further in understanding the biological mechanism. Finally, a clinical evaluation was performed to confirm the tan boosting effect of this innovative ingredient.
Seppic Research & Innovation, Paris La Défense, La Garenne Colombes